The story of King Joash of Judah starts with that of King Jehu of Israel. Anointed king of Israel by Elisha, Jehu was tasked with destroying King Ahab’s descendants and wiping out Baal worship in the land (2 Kings 9). First Kings 21:25–26 gives the reason for the judgment: “There was never anyone like Ahab, who sold himself to do evil in the eyes of the Lord, urged on by Jezebel his wife. He behaved in the vilest manner by going after idols, like the Amorites the Lord drove out before Israel.” God had told Ahab, through Elijah, “I am going to bring disaster on you. I will wipe out your descendants and cut off from Ahab every last male in Israel—slave or free, . . . because you have aroused my anger and have caused Israel to sin” (1 Kings 21:21–22). Ahab responded to the prophecy with mourning and in humility, so God relented, saying that He would not bring the disaster in Ahab’s time but during his son’s reign. Jehu was God’s instrument to fulfill the prophecy.